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-   -   Implausible fuel maps? (https://www.rx7club.com/engine-management-forum-37/implausible-fuel-maps-1064283/)

Vicoor 05-21-14 07:42 PM

Implausible fuel maps?
 
Whats the deal?

I'm trying to come up with a "base tune" to get started on, and the fuel maps I keep finding have injector pulse widths exceeding 6,7,8,9mS and sometimes even higher.

The way I see it at 8000rpm the rotary engine is doing one revoultion every 7.5mS and if you were keeping the duty cycle below 80% you would have to limit the pulse width to 6.0mS

Even the canned base maps from haltech have implausible values

It worries me about all other values in the IGN tables, etc...

EB Turbo 05-22-14 03:01 PM


Originally Posted by Vicoor (Post 11740664)
Whats the deal?

I'm trying to come up with a "base tune" to get started on, and the fuel maps I keep finding have injector pulse widths exceeding 6,7,8,9mS and sometimes even higher.

The way I see it at 8000rpm the rotary engine is doing one revoultion every 7.5mS and if you were keeping the duty cycle below 80% you would have to limit the pulse width to 6.0mS

Even the canned base maps from haltech have implausible values

It worries me about all other values in the IGN tables, etc...

Depending on any type of manifold pressure compensations, staged injection split, air temp, coolant temp, those numbers will change. Also depending on inj size the numbers will change. Then you also deal with inj timing. You may be starting the injection on a closed port.

EB Turbo

Vicoor 05-25-14 12:39 PM

The Base fuel table is the manifold pressure correction, and while I guess there would be times you might pull some fuel, If the table goes over 6.0mS at 9000 RPM in the Fifteen top right most cells, you are not doing anything to control the fuel.

So If this "Minor Detail" is so obviously wrong, what about the rest of the tune.

Should I expect to just cross my fingers and say a prayer the first time I try to run it?

EB Turbo 05-28-14 03:03 PM


Originally Posted by Vicoor (Post 11742361)
The Base fuel table is the manifold pressure correction,

This depends on the ECU and the person setting up the tune. most of the ECUs i use have either a 2D or 3D secondary load table which I use all of the time.


..So If this "Minor Detail" is so obviously wrong, what about the rest of the tune.

Should I expect to just cross my fingers and say a prayer the first time I try to run it?
Some people start off with way worse. If you really want to get a good starting point, you can see where the car wants to idle and then do the math to fill in the positive manifold pressure rows.

EB Turbo


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